It’s long been assumed by science that animals need to exert pressure on the ground, air or water in order to move, whether they’re walking, running, swimming or flying. With this pressure comes the ability to move forward but a recent study published on Tuesday may change the way we think about momentum and movement.
The study uses jellyfish and lamprey eels to demonstrate that rather than pushing water backwards, they ‘pull’ themselves forward through creating a region of low pressure in the water ahead of them. The findings were published in the journal, Nature Communications and were carried out by the University of Stanford’s John Dabiri and his team of engineers and biologists.
Dabiri and his team studied jellyfish and lampreys while they swam through water tunnels equipped with glass beads to make the motions in the water visible. They used high-speed digital imagery and computer generated pressure measurements to record ‘flow fields’ around the animals. The team discovered that low-pressure regions were the most dominant forces in the water.
Dabiri said “the low pressure is created on the top of the jellyfish’s umbrella-shaped body, which is different from our previous understanding of their swimming dynamics that focused on the flow underneath the umbrella…we have shown that the mechanism of efficient swimming is much different than conventional wisdom.”
Based on this new information it could potentially lead to designing more energy-efficient submarines and other vehicles. This is because high pressure is generated through pushing liquid molecules together such as the hand motions of a human. Low pressure is created in various ways, such as rotating the body. This low pressure method therefore requires less energy.
The data also challenges our assumptions about animal evolution according to Dabiri. “Animal mobility is known to be important for determining the fitness of species and hence their captivity in survival. Prior to this work, the assumption…had been that generating high pressure is essential for effective motility.”
This evolutionary adaptation means that jellyfish and lampreys save more energy while swimming than any other animal. This discovery is fascinating and proves that we’re still learning new things about evolution and the resiliency of animals in their own environments.